The issue of detention as a public health control measure has attracted attention recently. This is because the threat of strains of tuberculosis that are resistant to a wider range of drugs has been identified, and there is renewed concern that public health is threatened. This paper considers whether involuntary detention is justified where voluntary measures have failed or where a patient poses a danger, albeit uncertain, to the public. We discuss the need for strengthening evidence-based assessments of public health risk and suggest that we should refect more profoundly on the philosophical foundations upon which our policies and practices are grounded